The automobile has come a long way in the past 100 years, and I expect there will be a lot of new technological developments in the next 50 years or so. I can't think of anything right now that would replace the internal combustion engine, but it IS quite likely that by 2085, people will be using a much different source of fuel for their transportation.
Hydrogen is the future, the prototypes are already here. We are just conditioned to using a noisy petrol engine - because sometimes that noise is just spine-tingling!
Don't know your timeline - but, yes. They will likely be smaller, and have forced air induction for better performance.
They will until we run out of oil, or it becomes too expensive to use.
